Venezuelan President Hugo Chavez kisses a crucifix as he speaks during a national broadcast at Miraflores Palace in Caracas December 9, 2012. [Photo/Agencies]

CARACAS - Venezuela's Hugo Chavez said on Saturday that his cancer had returned and he would undergo another operation in the coming days, and for the first time the president named a successor if anything happened to him.

The news was a big blow for supporters of the 58-year-old socialist leader, who elected him in October to a new six-year term in office. Twice since mid-2011 Chavez has said he was cured, and then had to have more surgery.

In an emotional television broadcast from the Miraflores presidential palace, Chavez was flanked by ministers and looked resolute. He even sang, briefly. And in his first comments on a possible successor, he said supporters should vote for Vice President Nicolas Maduro.

Speculation about Chavez's health had grown during a three-week absence from public view that culminated in his latest trip for medical tests in Cuba - where he has undergone three cancer operations since June 2011. He returned to Venezuela on Friday.

"Unfortunately, during these exhaustive exams they found some malignant cells in the same (pelvic) area ... . It is absolutely necessary, absolutely essential, that I undergo a new surgical intervention," the president said.

"With God's will, like on the previous occasions, we will come out of this victorious. I have complete faith in that."

Chavez, who has dominated Venezuelan politics since taking power 14 years ago, said he would return to Cuba on Sunday, and that the operation would take place there in next few days.

He said he had rejected the advice of his doctors to have the surgery sooner, on Friday or this weekend, telling them he needed to fly back to Venezuela to seek the permission of lawmakers to return for the operation.

"I decided to come, making an additional effort, in truth, because the pain is not insignificant," Chavez said. "But with treatment and painkillers, we are in the pre-operation phase."